Pneumatic tire

ABSTRACT

The present invention is directed to a pneumatic tire having a tread comprising a vulcanizable rubber composition comprising, based on 100 parts by weight of elastomer (phr),(A) from about 45 to about 100 phr of a low-cis polybutadiene having a vinyl-1,2 content ranging from 5 to 30 percent and a Tg ranging from −95° C. to −70° C.;(B) from about 0 to about 40 phr of a solution polymerized styrene-butadiene rubber having a glass transition temperature (Tg) ranging from −85° C. to −50° C.;(C) from 0 to 30 phr of natural rubber or synthetic polyisoprene;(D) from 0 to 20 phr of a process oil;(E) from 55 to 80 phr of a resin having an aromatic hydrogen content ranging from 3 to 30 mole percent, the resin having a Tg greater than 30° C.; and(F) from 110 to 160 phr of silica.

BACKGROUND OF THE INVENTION

It is highly desirable for tires to have good wet skid resistance, lowrolling resistance, and good wear characteristics. It has traditionallybeen very difficult to improve a tire's wear characteristics withoutsacrificing its wet skid resistance and traction characteristics. Theseproperties depend, to a great extent, on the dynamic viscoelasticproperties of the rubbers utilized in making the tire.

In order to reduce the rolling resistance and to improve the treadwearcharacteristics of tires, rubbers having a high rebound havetraditionally been utilized in making tire tread rubber compounds. Onthe other hand, in order to increase the wet skid resistance of a tire,rubbers which undergo a large energy loss have generally been utilizedin the tire's tread. In order to balance these two viscoelasticallyinconsistent properties, mixtures of various types of synthetic andnatural rubber are normally utilized in tire treads.

Tires are sometimes desired with treads for promoting traction on snowysurfaces. Various rubber compositions may be proposed for tire treads.Here, the challenge is to reduce the cured stiffness of such treadrubber compositions, as indicated by having a lower storage modulus G′at −20° C., when the tread is intended to be used for low temperaturewinter conditions, particularly for vehicular snow driving.

It is considered that significant challenges are presented for providingsuch tire tread rubber compositions for maintaining both their wettraction while promoting low temperature (e.g. winter) performance.

SUMMARY OF THE INVENTION

The present invention is directed to a pneumatic tire having a treadcomprising a vulcanizable rubber composition comprising, based on 100parts by weight of elastomer (phr),

(A) from about 45 to about 100 phr of a low-cis polybutadiene having avinyl-1,2 content ranging from 5 to 30 percent and a Tg ranging from−95° C. to −70° C.;

(B) from about 0 to about 40 phr of a solution polymerizedstyrene-butadiene rubber having a glass transition temperature (Tg)ranging from −85° C. to −50° C.;

(C) from 0 to 30 phr of natural rubber or synthetic polyisoprene;

(D) from 0 to 20 phr of a process oil;

(E) from 55 to 80 phr of a resin having an aromatic hydrogen contentranging from 3 to 30 mole percent, the resin having a Tg greater than30° C.; and

(F) from 110 to 160 phr of silica.

The invention is further directed to a method of making a tire.

DESCRIPTION OF THE INVENTION

There is disclosed a pneumatic tire having a tread comprising avulcanizable rubber composition comprising, based on 100 parts by weightof elastomer (phr),

(A) from about 45 to about 100 phr of a low-cis polybutadiene having avinyl-1,2 content ranging from 5 to 30 percent and a Tg ranging from−95° C. to −70° C.;

(B) from about 0 to about 40 phr of a solution polymerizedstyrene-butadiene rubber having a glass transition temperature (Tg)ranging from −85° C. to −50° C.;

(C) from 0 to 30 phr of natural rubber or synthetic polyisoprene;

(D) from 0 to 20 phr of a process oil;

(E) from 55 to 80 phr of a resin having an aromatic hydrogen contentranging from 3 to 30 mole percent, the resin having a Tg greater than30° C.; and

(F) from 110 to 160 phr of silica.

There is further disclosed a method of making a tire.

One component of the rubber composition is from about 45 to about 100phr, alternatively 55 to 80 phr, of a polybutadiene.

In one embodiment, the polybutadiene is a low cis polybutadiene has avinyl-1,2 content of from 5 to 30 percent and a Tg in a range of from−95 to −70 C. Such low cis polybutadiene typical consist of each of thecis-1,4/trans-1,4/vinyl-1,2 monomer insertions are no more than 50percent in the polybutadiene polymer chain, and is produced via anionicsolution polymerization with a lithium catalyst. In one embodiment, thelow cis polybutadiene includes from 10 to 30 percent vinyl 1,2; from 15to 45 percent cis-1,4; and the balance trans-1,4 to make up 100 percentof the polymer. In one embodiment, the low cis polybutadiene is SEPB-5800 from Trinseo, with about 11% vinyl-1,2, 39% cis-1,4 and 50%trans-1,4 insertions and a Tg of about −90° C.

In one embodiment, the low cis polybutadiene is a functionalized low cispolybutadiene. Such functionalized low cis polybutadiene may be one ormore functional groups appended to the polymer chain at either terminusor in-chain. Functional groups may be incorporated during polymerizationas a function initiator or function terminator for terminal appendage,or as a functional monomer for in-chain insertion. Functional groups mayinclude hydroxyl, amino, alkoxy, alkoxyamine, thiol, silane,alkoxysilane, alkoxyaminosilane, and the like. Such functional groupsimpart the ability of the functionalized low-cis polybutadiene to reactwith surface active groups such as hydroxyl groups on silica tofacilitate dispersion and interaction between the silica and low-cispolybutadiene mixed in a rubber compound.

The rubber composition includes from 0 to 40 phr, alternatively 20 to 40phr, of a styrene-butadiene rubber having a glass transition temperature(Tg) ranging from −85° C. to −50° C. The styrene-butadiene rubber may befunctionalized with various functional groups, or the styrene-butadienerubber may be non-functionalized. In on embodiment the styrene-butadienerubber is functionalized with an alkoxysilane group and at least one ofa primary amine group and thiol group. In one embodiment, thestyrene-butadiene rubber is obtained by copolymerizing styrene andbutadiene, and characterized in that the styrene-butadiene rubber has aprimary amino group and/or thiol group and an alkoxysilyl group whichare bonded to the polymer chain. In one embodiment, the alkoxysilylgroup is an ethoxysilyl group. In one embodiment, the styrene-butadienerubber is not functionalized.

The primary amino group and/or thiol group may be bonded to any of apolymerization initiating terminal, a polymerization terminatingterminal, a main chain of the styrene-butadiene rubber and a side chain,as long as it is bonded to the styrene-butadiene rubber chain. However,the primary amino group and/or thiol group is preferably introduced tothe polymerization initiating terminal or the polymerization terminatingterminal, in that the disappearance of energy at a polymer terminal isinhibited to improve hysteresis loss characteristics.

Further, the content of the alkoxysilyl group bonded to the polymerchain of the (co)polymer rubber is preferably from 0.5 to 200 mmol/kg ofstyrene-butadiene rubber. The content is more preferably from 1 to 100mmol/kg of styrene-butadiene rubber, and particularly preferably from 2to 50 mmol/kg of styrene-butadiene rubber.

The alkoxysilyl group may be bonded to any of the polymerizationinitiating terminal, the polymerization terminating terminal, the mainchain of the (co)polymer and the side chain, as long as it is bonded tothe (co)polymer chain. However, the alkoxysilyl group is preferablyintroduced to the polymerization initiating terminal or thepolymerization terminating terminal, in that the disappearance of energyis inhibited from the (co)polymer terminal to be able to improvehysteresis loss characteristics.

The styrene-butadiene rubber can be produced by polymerizing styrene andbutadiene in a hydrocarbon solvent by anionic polymerization using anorganic alkali metal and/or an organic alkali earth metal as aninitiator, adding a terminating agent compound having a primary aminogroup protected with a protective group and/or a thiol group protectedwith a protecting group and an alkoxysilyl group to react it with aliving polymer chain terminal at the time when the polymerization hassubstantially completed, and then conducting deblocking, for example, byhydrolysis or other appropriate procedure. In one embodiment, thestyrene-butadiene rubber can be produced as disclosed in U.S. Pat. No.7,342,070. In another embodiment, the styrene-butadiene rubber can beproduced as disclosed in WO 2007/047943.

In one embodiment, and as taught in U.S. Pat. No. 7,342,070, thestyrene-butadiene rubber is of the formula (I) or (II)

wherein P is a (co)polymer chain of a conjugated diolefin or aconjugated diolefin and an aromatic vinyl compound, R¹ is an alkylenegroup having 1 to 12 carbon atoms, R² and R³ are each independently analkyl group having 1 to 20 carbon atoms, an allyl group or an arylgroup, n is an integer of 1 or 2, m is an integer of 1 or 2, and k is aninteger of 1 or 2, with the proviso that n+m+k is an integer of 3 or 4,

wherein P, R¹, R² and R³ have the same definitions as give for theabove-mentioned formula I, j is an integer of 1 to 3, and h is aninteger of 1 to 3, with the provision that j+h is an integer of 2 to 4.

The terminating agent compound having a protected primary amino groupand an alkoxysilyl group may be any of various compounds as are known inthe art. In one embodiment, the compound having a protected primaryamino group and an alkoxysilyl group may include, for example,N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane,1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane,N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane,N,N-bis(trimethylsilyl)aminopropyltriethoxysilane,N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane,N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane,N,N-bis(trimethylsilyl)-aminoethyltriethoxysilne,N,N-bis(trimethylsilyl)aminoethylmethyldimethoxysilane,N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane, etc., andpreferred are 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane,N,N-bis(trimethylsilyl) aminopropylmethyldimethoxysilane andN,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane. In oneembodiment, the compound having a protected primary amino group and analkoxysilyl group is N,N-bis(trimethylsilyl)aminopropyltriethoxysilane.

In one embodiment, the compound having a protected primary amino groupand an alkoxysilyl group may be any compound of formula III

RN—(CH₂)_(x)Si(OR′)₃,  III

wherein R in combination with the nitrogen (N) atom is a protected aminegroup which upon appropriate post-treatment yields a primary amine, R′represents a group having 1 to 18 carbon atoms selected from an alkyl, acycloalkyl, an allyl, or an aryl; and X is an integer from 1 to 20. Inone embodiment, at least one R′ group is an ethyl radical. Byappropriate post-treatment to yield a primary amine, it is meant thatsubsequent to reaction of the living polymer with the compound having aprotected primary amino group and an alkoxysilyl group, the protectinggroups are removed. For example, in the case of bis(trialkylsilyl)protecting group as inN,N-bis(trimethylsilyl)aminopropyltriethoxysilane, hydrolysis is used toremove the trialkylsilyl groups and leave the primary amine.

In one embodiment, the rubber composition includes from about 40 toabout 60 phr of styrene-butadiene rubber functionalized with analkoxysilane group and a primary amine group or thiol group.

Suitable styrene-butadiene rubbers functionalized with an alkoxysilanegroup and a primary amine group are available commercially, such as HPR340 from Japan Synthetic Rubber (JSR).

In one embodiment, the solution polymerized styrene-butadiene rubber isas disclosed in WO 2007/047943 and is functionalized with analkoxysilane group and a thiol, and comprises the reaction product of aliving anionic polymer and a silane-sulfide modifier represented by theformula IV

(R⁴O)_(x)R⁴ _(y)Si—R⁵—S—SiR⁴ ₃  IV

wherein Si is silicon; S is sulfur; O is oxygen; x is an integerselected from 1, 2 and 3;y is an integer selected from 0, 1, and 2;x+y=3;R⁴ is the same or different and is (C₁-C₁₆) alkyl; and R′ is aryl,and alkyl aryl, or (C₁-C₁₆) alkyl. In one embodiment, R⁵ is a (C₁-C₁₆)alkyl. In one embodiment, each R⁴ group is the same or different, andeach is independently a C₁-C₅ alkyl, and R⁵ is C₁-C₅ alkyl.

The solution polymerized styrene-butadiene rubber has a glass transitiontemperature in a range from −85° C. to −50° C. A reference to glasstransition temperature, or Tg, of an elastomer or elastomer composition,where referred to herein, represents the glass transition temperature(s)of the respective elastomer or elastomer composition in its uncuredstate or possibly a cured state in a case of an elastomer composition. ATg can be suitably determined as a peak midpoint by a differentialscanning calorimeter (DSC) at a temperature rate of increase of 10° C.per minute, for example according to ASTM D7426 or equivalent.

Suitable styrene-butadiene rubbers functionalized with an alkoxysilanegroup and a thiol group are available commercially, such as Sprintan SLR3402 from Trinseo.

Another component of the rubber composition is from about 0 to about 30phr, alternatively from 10 to 30 phr, of natural rubber or syntheticpolyisoprene. In one embodiment, the rubber composition comprises from15 to 25 phr of natural rubber or synthetic polyisoprene. In oneembodiment, the rubber composition comprises from 5 to 15 phr of naturalrubber or synthetic polyisoprene.

The rubber composition may include 0 to 20 phr, alternatively 1 to 20phr, of a processing oil. Processing oil may be included in the rubbercomposition as extending oil typically used to extend elastomers.Processing oil may also be included in the rubber composition byaddition of the oil directly during rubber compounding. The processingoil used may include both extending oil present in the elastomers, andprocess oil added during compounding. Suitable process oils includevarious oils as are known in the art, including aromatic, paraffinic,naphthenic, and low PCA oils, such as MES, TDAE, and heavy naphthenicoils, vegetable oils such as sunflower, soybean, and safflower oils, andmonoesters of fatty acids selected from the group consisting of alkyloleates, alkyl stearates, alkyl linoleates, and alkyl palmitates.

Suitable low PCA oils include those having a polycyclic aromatic contentof less than 3 percent by weight as determined by the IP346 method.Procedures for the IP346 method may be found in Standard Methods forAnalysis & Testing of Petroleum and Related Products and BritishStandard 2000 Parts, 2003, 62nd edition, published by the Institute ofPetroleum, United Kingdom.

Suitable TDAE oils are available as Tudalen SX500 from Klaus Dahleke KG,VivaTec 400 and VivaTec 500 from H&R Group, and Enerthene 1849 from BP,and Extensoil 1996 from Repsol.

The oils may be available as the oil alone or along with an elastomer inthe form of an extended elastomer.

Suitable vegetable oils include, for example, soybean oil, sunflower oiland canola oil which are in the form of esters containing a certaindegree of unsaturation.

The rubber composition further includes from 50 to 80 phr, alternatively55 to 80 phr, of a resin. In one embodiment, the resin is selected fromC5/C9 resins and dicyclopentadiene (DCPD)/C9 resins.

In one embodiment, the resin is a C5/C9 hydrocarbon resin comprising C5and C9 hydrocarbon fractions, wherein the resin has a glass transitiontemperature greater than 30° C. A suitable measurement of Tg for resinsis DSC according to ASTM D6604 or equivalent. The hydrocarbon resin hasa softening point between 0° C. and 160° C. as determined by ASTM E28which might sometimes be referred to as a ring and ball softening point.

Suitable C5/C9 resins may include both aromatic and nonaromaticcomponents. Differences in the C5/C9 resins are largely due to theolefins in the feedstock from which the hydrocarbon components arederived. The C5/C9 resin may contain “aliphatic” hydrocarbon componentswhich have a hydrocarbon chain formed from C4-C6 fractions containingvariable quantities of piperylene, isoprene, mono-olefins, andnon-polymerizable paraffinic compounds. Such C5/C9 resins are based onpentene, butane, isoprene, piperylene, and contain reduced quantities ofcyclopentadiene or dicyclopentadiene. The C5/C9 resin may also contain“aromatic” hydrocarbon structures having polymeric chains which areformed of aromatic units, such as styrene, xylene,.alpha.-methylstyrene, vinyl toluene, and indene.

In accordance with the present invention, the C5/C9 resin used in rubbercompounding includes olefins such as piperylene, isoprene, amylenes, andcyclic components. The C5/C9 resin may also contain aromatic olefinssuch as styrenic components and indenic components.

Piperylenes are generally a distillate cut or synthetic mixture of C5diolefins, which include, but are not limited to, cis-1,3-pentadiene,trans-1,3-pentadiene, and mixed 1,3-pentadiene. In general, piperylenesdo not include branched C5 diolefins such as isoprene. In oneembodiment, the C5/C9 resin has from 40 to 90% (by weight) piperylene,or from 50 to 90%, or more preferably from 60 to 90%. In a particularlypreferred embodiment, the C5/C9 resin has from 70 to 90% piperylene.

In one embodiment, the C5/C9 resin is substantially free of isoprene. Inanother embodiment, the C5/C9 resin contains up to 15% isoprene, or lessthan 10% isoprene. In yet another embodiment, the C5/C9 resin containsless than 5% isoprene.

In one embodiment, the C5/C9 resin is substantially free of amylene. Inanother embodiment, the C5/C9 resin contains up to 40% amylene, or lessthan 30% amylene, or less than 25% amylene. In yet another embodiment,the C5/C9 resin contains up to 10% amylene.

Cyclics are generally a distillate cut or synthetic mixture of C5 and C6cyclic olefins, diolefins, and dimers therefrom. Cyclics include, butare not limited to, cyclopentene, cyclopentadiene, dicyclopentadiene,cyclohexene, 1,3-cycylohexadiene, and 1,4-cyclohexadiene. A preferredcyclic is cyclopentadiene. The dicyclopentadiene may be in either theendo or exo form. The cyclics may or may not be substituted. Preferredsubstituted cyclics include cyclopentadienes and dicyclopentadienessubstituted with a C1 to C40 linear, branched, or cyclic alkyl group,preferably one or more methyl groups. In one embodiment the C5/C9 resinmay include up to 60% cyclics or up to 50% cyclics. Typical lower limitsinclude at least about 0.1% or at least about 0.5% or from about 1.0%cyclics are included. In at least one embodiment, the C5/C9 resin mayinclude up to 20% cyclics or more preferably up to 30% cyclics. In aparticularly preferred embodiment, the C5/C9 resin comprises from about1.0 to about 15% cyclics, or from about 5 to about 15% cyclics.

Preferred aromatics that may be in the C5/C9 resin include one or moreof styrene, indene, derivatives of styrene, and derivatives of indene.Particularly preferred aromatic olefins include styrene,alpha-methylstyrene, beta-methylstyrene, indene, and methylindenes, andvinyl toluenes. The aromatic olefins are typically present in the C5/C9resin from 5 to 45%, or more preferably from 5 to 30%. In particularlypreferred embodiments, the C5/C9 resin comprises from 10 to 20% aromaticolefins.

Styrenic components include styrene, derivatives of styrene, andsubstituted sytrenes. In general, styrenic components do not includefused-rings, such as indenics. In one embodiment, the C5/C9 resincomprises up to 60% styrenic components or up to 50% styreniccomponents. In one embodiment, the C5/C9 resin comprises from 5 to 30%styrenic components, or from 5 to 20% styrenic components. In apreferred embodiment, the C5/C9 resin comprises from 10 to 15% styreniccomponents.

The C5/C9 resin may comprise less than 15% indenic components, or lessthan 10% indenic components. Indenic components include indene andderivatives of indene. In one embodiment, the C5/C9 resin comprises lessthan 5% indenic components. In another embodiment, the C5/C9 resin issubstantially free of indenic components.

Preferred C5/C9 resins have melt viscosity of from 300 to 800 centipoise(cPs) at 160 C, or more preferably of from 350 to 650 cPs at 160 C. In aparticularly preferred embodiment, the C5/C9 resin's melt viscosity isfrom 375 to 615 cPs at 160 C., or from 475 to 600 cPs at 160 C. The meltviscosity may be measured by a Brookfield viscometer with a type “J”spindle, ASTM D6267.

Generally C5/C9 resins have a weight average molecular weight (Mw)greater than about 600 g/mole or greater than about 1000 g/mole. In atleast one embodiment, C5/C9 resins have a weight average molecularweight (Mw) of from 1650 to 1950 g/mole, or from 1700 to 1900 g/mole.Preferably C5/C9 resins have a weight average molecular weight of from1725 to 1890 g/mole. The C5/C9 resin may have a number average molecularweight (Mn) of from 450 to 700 g/mole, or from 500 to 675 g/mole, ormore preferably from 520 to 650 g/mole. The C5/C9 resin may have az-average molecular weight (Mz) of from 5850 to 8150 g/mole, or morepreferably from 6000 to 8000 g/mole. Mw, Mn, and Mz may be determined bygel permeation chromatography (GPC).

In one embodiment the C5/C9 resin has a polydispersion index (“PDI”,PDI=Mw/Mn) of 4 or less. In a particularly preferred embodiment theC5/C9 resin has a PDI of from 2.6 to 3.1.

Preferred C5/C9 resins have a glass transition temperature (Tg) of fromabout −30 C to about 100 C, or from about 0 C. to 80 C, or from about40-60 C, or from 45-55 C, or more preferably of from 48-53.degree. C.Differential scanning calorimetry (DSC) may be used to determine theC5/C9 resin's Tg.

In another embodiment the C5/C9 resin may be hydrogenated.

In one embodiment, the C5/C9 resin comprises 50-90% (by weight)piperylene, 0-5% isoprene, 10-30% amylenes, 0-5% cyclics, 0-10%styrenics, and 0-10% indenics.

In one embodiment, the C5/C9 resin comprises 50-90% (by weight)piperylene, 0-5% isoprene, 10-30% amylenes, 2-5% cyclics, 4-10%styrenics, and 4-10% indenics.

In one embodiment, the C5/C9 comprises about 60% (by weight) piperylene,about 22% amylene, about 3% cyclics, about 6% styrene, and about 6%indene, and further has a melt viscosity at 160 C of 436 cPs; Mn of 855g/mole; Mw of 1595 g/mole; Mz of 3713 g/mole; PDI of 1.9; and Tg of 47C.

The resin, including but not limited to C5/C9 resin or DCPD/C9 resin,may further be characterized by its aromatic hydrogen content, asdetermined by 1H NMR. In one embodiment, the resin has an aromatichydrogen content ranging from 3 to 30 mole percent. In one embodiment,the resin has an aromatic hydrogen content less than 25 mole percent. Inone embodiment, the resin has an aromatic hydrogen content is between 3and 15 mole percent.

An example of a useful resin is the Oppera series of polymeric additivescommercially available from ExxonMobil Chemical Company, including butnot limited to Oppera 373.

In one embodiment, the resin is a DCPD/C9 resin. A suitable DCPD/C9resin is a hydrogenated DCPD/C9 resin available as Oppera 383 having anaromatic hydrogen content of about 10 mole percent.

The phrase “rubber or elastomer containing olefinic unsaturation” isintended to include both natural rubber and its various raw and reclaimforms as well as various synthetic rubbers. In the description of thisinvention, the terms “rubber” and “elastomer” may be usedinterchangeably, unless otherwise prescribed. The terms “rubbercomposition,” “compounded rubber” and “rubber compound” are usedinterchangeably to refer to rubber which has been blended or mixed withvarious ingredients and materials, and such terms are well known tothose having skill in the rubber mixing or rubber compounding art.

The vulcanizable rubber composition may include from about 1100 to about160 phr of silica.

The commonly employed siliceous pigments which may be used in the rubbercompound include conventional pyrogenic and precipitated siliceouspigments (silica), although precipitated silicas are preferred. Theconventional siliceous pigments preferably employed in this inventionare precipitated silicas such as, for example, those obtained by theacidification of a soluble silicate, e.g., sodium silicate.

Such conventional silicas might be characterized, for example, by havinga BET surface area, as measured using nitrogen gas, preferably in therange of about 40 to about 600, and more usually in a range of about 50to about 300 square meters per gram. The BET method of measuring surfacearea is described in the Journal of the American Chemical Society,Volume 60, Page 304 (1930).

The conventional silica may also be typically characterized by having adibutylphthalate (DBP) absorption value in a range of about 100 to about400, and more usually about 150 to about 300.

The conventional silica might be expected to have an average ultimateparticle size, for example, in the range of 0.01 to 0.05 micron asdetermined by the electron microscope, although the silica particles maybe even smaller, or possibly larger, in size.

Various commercially available silicas may be used, such as, only forexample herein, and without limitation, silicas commercially availablefrom PPG Industries under the Hi-Sil trademark with designations 210,243, 315 etc.; silicas available from Rhodia, with, for example,designations of Z1165MP and Z165GR and silicas available from Degussa AGwith, for example, designations VN2 and VN3, etc.

Pre-hydrophobated precipitated silica may be used. By pre-hydrophobated,it is meant that the silica is pretreated, i.e., the pre-hydrophobatedprecipitated silica is hydrophobated prior to its addition to the rubbercomposition by treatment with at least one silane. Suitable silanesinclude but are not limited to alkylsilanes, alkoxysilanes,organoalkoxysilyl polysulfides and organomercaptoalkoxysilanes.Alternatively, the precipitated silica may be pre-treated with a silicacoupling agent comprised of, for example, an alkoxyorganomercaptosilaneor combination of alkoxysilane and alkoxyorganomercaptosilane prior toblending the pre-treated silica with the rubber instead of reacting theprecipitated silica with the silica coupling agent in situ within therubber. For example, see U.S. Pat. No. 7,214,731. For variouspre-treated precipitated silicas see, for example, U.S. Pat. Nos.4,704,414, 6,123,762 and 6,573,324. Suitable pre-treated orpre-hydrophobated silica is available commercially for example as Agilon400 from PPG.

The vulcanizable rubber composition may include from about 1 to about 20phr of carbon black.

Commonly employed carbon blacks can be used as a conventional filler.Representative examples of such carbon blacks include N110, N121, N134,N220, N231, N234, N242, N293, N299, S315, N326, N330, M332, N339, N343,N347, N351, N358, N375, N539, N550, N582, N630, N642, N650, N683, N754,N762, N765, N774, N787, N907, N908, N990 and N991. These carbon blackshave iodine absorptions ranging from 9 to 145 g/kg and DBP numberranging from 34 to 150 cm³/100 g.

It may be preferred to have the rubber composition for use in the tirecomponent to additionally contain a conventional sulfur containingorganosilicon compound. Examples of suitable sulfur containingorganosilicon compounds are of the formula:

Z-Alk-S_(n)-Alk-Z  V

in which Z is selected from the group consisting of

where R⁶ is an alkyl group of 1 to 4 carbon atoms, cyclohexyl or phenyl;R⁷ is alkoxy of 1 to 8 carbon atoms, or cycloalkoxy of 5 to 8 carbonatoms; Alk is a divalent hydrocarbon of 1 to 18 carbon atoms and n is aninteger of 2 to 8.

Specific examples of sulfur containing organosilicon compounds which maybe used in accordance with the present invention include:3,3′-bis(trimethoxysilylpropyl) disulfide, 3,3′-bis(triethoxysilylpropyl) disulfide, 3,3′-bis(triethoxysilylpropyl)tetrasulfide, 3,3′-bis(triethoxysilylpropyl) octasulfide,3,3′-bis(trimethoxysilylpropyl) tetrasulfide,2,2′-bis(triethoxysilylethyl) tetrasulfide,3,3′-bis(trimethoxysilylpropyl) trisulfide,3,3′-bis(triethoxysilylpropyl) trisulfide,3,3′-bis(tributoxysilylpropyl) disulfide,3,3′-bis(trimethoxysilylpropyl) hexasulfide,3,3′-bis(trimethoxysilylpropyl) octasulfide,3,3′-bis(trioctoxysilylpropyl) tetrasulfide,3,3′-bis(trihexoxysilylpropyl) disulfide,3,3′-bis(tri-2″-ethylhexoxysilylpropyl) trisulfide,3,3′-bis(triisooctoxysilylpropyl) tetrasulfide,3,3′-bis(tri-t-butoxysilylpropyl) disulfide, 2,2′-bis(methoxy diethoxysilyl ethyl) tetrasulfide, 2,2′-bis(tripropoxysilylethyl) pentasulfide,3,3′-bis(tricyclonexoxysilylpropyl) tetrasulfide,3,3′-bis(tricyclopentoxysilylpropyl) trisulfide,2,2′-bis(tri-2″-methylcyclohexoxysilylethyl) tetrasulfide,bis(trimethoxysilylmethyl) tetrasulfide, 3-methoxy ethoxy propoxysilyl3′-diethoxybutoxy-silylpropyltetrasulfide, 2,2′-bis(dimethylmethoxysilylethyl) disulfide, 2,2′-bis(dimethyl sec.butoxysilylethyl)trisulfide, 3,3′-bis(methyl butylethoxysilylpropyl) tetrasulfide,3,3′-bis(di t-butylmethoxysilylpropyl) tetrasulfide, 2,2′-bis(phenylmethyl methoxysilylethyl) trisulfide, 3,3′-bis(diphenylisopropoxysilylpropyl) tetrasulfide, 3,3′-bis(diphenylcyclohexoxysilylpropyl) disulfide, 3,3′-bis(dimethylethylmercaptosilylpropyl) tetrasulfide, 2,2′-bis(methyldimethoxysilylethyl) trisulfide, 2,2′-bis(methylethoxypropoxysilylethyl) tetrasulfide, 3,3′-bis(diethylmethoxysilylpropyl) tetrasulfide, 3,3′-bis(ethyl di-sec.butoxysilylpropyl) disulfide, 3,3′-bis(propyl diethoxysilylpropyl)disulfide, 3,3′-bis(butyl dimethoxysilylpropyl) trisulfide,3,3′-bis(phenyl dimethoxysilylpropyl) tetrasulfide, 3-phenylethoxybutoxysilyl 3′-trimethoxysilylpropyl tetrasulfide,4,4′-bis(trimethoxysilylbutyl) tetrasulfide,6,6′-bis(triethoxysilylhexyl) tetrasulfide,12,12′-bis(triisopropoxysilyl dodecyl) disulfide,18,18′-bis(trimethoxysilyloctadecyl) tetrasulfide,18,18′-bis(tripropoxysilyloctadecenyl) tetrasulfide,4,4′-bis(trimethoxysilyl-buten-2-yl) tetrasulfide,4,4′-bis(trimethoxysilylcyclohexylene) tetrasulfide,5,5′-bis(dimethoxymethylsilylpentyl) trisulfide,3,3′-bis(trimethoxysilyl-2-methylpropyl) tetrasulfide,3,3′-bis(dimethoxyphenylsilyl-2-methylpropyl) disulfide.

The preferred sulfur containing organosilicon compounds are the3,3′-bis(trimethoxy or triethoxy silylpropyl) sulfides. The mostpreferred compounds are 3,3′-bis(triethoxysilylpropyl) disulfide and3,3′-bis(triethoxysilylpropyl) tetrasulfide. Therefore, as to formula V,preferably Z is

where R⁷ is an alkoxy of 2 to 4 carbon atoms, with 2 carbon atoms beingparticularly preferred; alk is a divalent hydrocarbon of 2 to 4 carbonatoms with 3 carbon atoms being particularly preferred; and n is aninteger of from 2 to 5 with 2 and 4 being particularly preferred.

In another embodiment, suitable sulfur containing organosiliconcompounds include compounds disclosed in U.S. Pat. No. 6,608,125. In oneembodiment, the sulfur containing organosilicon compounds includes3-(octanoylthio)-1-propyltriethoxysilane, CH₃(CH₂)₆C(═O)—S—CH₂CH₂CH₂Si(OCH₂CH₃)₃, which is available commercially as NXT™ fromMomentive Performance Materials.

In one embodiment, the sulfur containing organosilicon compounds includethe reaction product of hydrocarbon based diol (e.g.,2-methyl-1,3-propanediol) with S-[3-(triethoxysilyl)propyl]thiooctanoate. In one embodiment, the sulfur containing organosiliconcompound is NXT-Z™ from Momentive Performance Materials.

In another embodiment, suitable sulfur containing organosiliconcompounds include those disclosed in U.S. Patent Publication No.2003/0130535. In one embodiment, the sulfur containing organosiliconcompound is Si-363 from Degussa.

The amount of the sulfur containing organosilicon compound of formula Iin a rubber composition will vary depending on the level of otheradditives that are used. Generally speaking, the amount of the compoundof formula I will range from 0.5 to 20 phr. Preferably, the amount willrange from 1 to 10 phr.

It is readily understood by those having skill in the art that therubber composition would be compounded by methods generally known in therubber compounding art, such as mixing the various sulfur-vulcanizableconstituent rubbers with various commonly used additive materials suchas, for example, sulfur donors, curing aids, such as activators andretarders and processing additives, fillers, pigments, fatty acid, zincoxide, waxes, antioxidants and antiozonants and peptizing agents. Asknown to those skilled in the art, depending on the intended use of thesulfur vulcanizable and sulfur-vulcanized material (rubbers), theadditives mentioned above are selected and commonly used in conventionalamounts. Representative examples of sulfur donors include elementalsulfur (free sulfur), an amine disulfide, polymeric polysulfide andsulfur olefin adducts. Preferably, the sulfur-vulcanizing agent iselemental sulfur. The sulfur-vulcanizing agent may be used in an amountranging from 0.5 to 8 phr, with a range of from 1 to 6 phr beingpreferred. Typical amounts of antioxidants comprise about 1 to about 5phr. Representative antioxidants may be, for example,diphenyl-p-phenylenediamine and others, such as, for example, thosedisclosed in The Vanderbilt Rubber Handbook (1978), pages 344 through346. Typical amounts of antiozonants comprise about 1 to 5 phr. Typicalamounts of fatty acids, if used, which can include stearic acid compriseabout 0.5 to about 5 phr. Typical amounts of zinc oxide comprise about 2to about 5 phr. Typical amounts of waxes comprise about 1 to about 5phr. Often microcrystalline waxes are used. Typical amounts of peptizerscomprise about 0.1 to about 1 phr. Typical peptizers may be, forexample, pentachlorothiophenol and dibenzamidodiphenyl disulfide.

Accelerators are used to control the time and/or temperature requiredfor vulcanization and to improve the properties of the vulcanizate. Inone embodiment, a single accelerator system may be used, i.e., primaryaccelerator. The primary accelerator(s) may be used in total amountsranging from about 0.5 to about 4, preferably about 0.8 to about 2.0,phr. In another embodiment, combinations of a primary and a secondaryaccelerator might be used with the secondary accelerator being used insmaller amounts, such as from about 0.05 to about 3 phr, in order toactivate and to improve the properties of the vulcanizate. Combinationsof these accelerators might be expected to produce a synergistic effecton the final properties and are somewhat better than those produced byuse of either accelerator alone. In addition, delayed actionaccelerators may be used which are not affected by normal processingtemperatures but produce a satisfactory cure at ordinary vulcanizationtemperatures. Vulcanization retarders might also be used. Suitable typesof accelerators that may be used in the present invention are amines,disulfides, guanidines, thioureas, thiazoles, thiurams, sulfenamides,dithiocarbamates and xanthates. Preferably, the primary accelerator is asulfenamide. If a second accelerator is used, the secondary acceleratoris preferably a guanidine, dithiocarbamate or thiuram compound.

The mixing of the rubber composition can be accomplished by methodsknown to those having skill in the rubber mixing art. For example, theingredients are typically mixed in at least two stages, namely, at leastone non-productive stage followed by a productive mix stage. The finalcuratives including sulfur-vulcanizing agents are typically mixed in thefinal stage which is conventionally called the “productive” mix stage inwhich the mixing typically occurs at a temperature, or ultimatetemperature, lower than the mix temperature(s) than the precedingnon-productive mix stage(s). The terms “non-productive” and “productive”mix stages are well known to those having skill in the rubber mixingart. The rubber composition may be subjected to a thermomechanicalmixing step. The thermomechanical mixing step generally comprises amechanical working in a mixer or extruder for a period of time suitablein order to produce a rubber temperature between 140° C. and 190° C. Theappropriate duration of the thermomechanical working varies as afunction of the operating conditions, and the volume and nature of thecomponents. For example, the thermomechanical working may be from 1 to20 minutes.

The rubber composition may be incorporated in a tread of a tire.

The pneumatic tire of the present invention may be a race tire,passenger tire, aircraft tire, agricultural, earthmover, off-the-road,truck tire, and the like. Preferably, the tire is a passenger or trucktire. The tire may also be a radial or bias, with a radial beingpreferred.

Vulcanization of the pneumatic tire of the present invention isgenerally carried out at conventional temperatures ranging from about100° C. to 200° C. Preferably, the vulcanization is conducted attemperatures ranging from about 110° C. to 180° C. Any of the usualvulcanization processes may be used such as heating in a press or mold,heating with superheated steam or hot air. Such tires can be built,shaped, molded and cured by various methods which are known and will bereadily apparent to those having skill in such art.

The following examples are presented for the purposes of illustratingand not limiting the present invention. All parts are parts by weightunless specifically identified otherwise.

Example 1

This example illustrates the advantage of a rubber composition accordingto the invention. Rubber compounds were mixed according to theformulations shown in Table 1 and 3, with amounts given in phr. Thecompounds were cured and tested for physical properties as shown inTables 2 and 4.

Tables 1-4 contain compound formulations utilizing a high loading levelof polybutadiene with a high loading level of traction resin of high andlow aromatic hydrogen contents. The inventive examples E1-4 containing alow aromatic hydrogen C5/C9 resin have superior properties compared tocomparative examples C1-4 containing a high aromatic hydrogen tractionresin in that they demonstrate a lower low temperature stiffness(characterized by lower G′ at 1.5% strain, −20° C.) indicative of bettertire snow traction, lower room temperature hysteresis (characterized byhigher Rebound at 23° C.) indicative of lower tire rolling resistanceand equivalent low temperature hysteresis (characterized by similarRebound at 0° C.) indicative of equivalent tire wet traction.

TABLE 1 Composition C1 E1 Styrene-butadiene ¹ 40 45 Polybutadiene ² 6055 Softener ³ 10 10 Antioxidant(s) 5.5 5.5 Stearic acid 5 5 Silane ⁴ 8.88.8 Silica ⁵ 140 140 Traction Resin A ⁶ 65 0 Traction Resin B ⁷ 0 65 ZnO2.5 2.5 Sulfur 1.2 1.2 Accelerator 6.0 6.0 ¹ Solution polymerized SBRwith styrene content of 15% and 1,2-vinyl content of 30%, Tg = −60° C.obtained from Trinseo as SLR3402. ² High cis polybutadiene, obtained asBudene 1223 from The Goodyear Tire & Rubber Company. ³ Sunflower oilobtained from Cargill as Agripure oil. ⁴ TESPD type silane couplingagent. ⁵ Hi-Sil 315G-D precipitated silica from PPG with a CTAB surfacearea of 125 m²/g ⁶ Copolymer of styrene and alpha-methylstyrene, Tg =+39° C., with an aromatic hydrogen content of about 53 mole % obtainedas Sylvatraxx4401 from Arizona Chemical. ⁷ Petroleum traction resin madeof C5 and C9 monomers, Tg = +46° C., with an aromatic hydrogen contentof about 4 mole %, obtained as Wingtack ET from Total Cray Valley.

TABLE 2 Composition C1 E1 Styrene-butadiene 40 45 Polybutadiene 60 55Softener 10 10 Traction Resin (A) 65 0 Traction Resin (B) 0 65 Dynamicproperties¹ G′ at 1% strain (MPa) 2.8 2.4 Wet grip property² Rebound at0° C. (%) 12.5 12.4 Low temperature property³ G′ at 1.5% strain, −20° C.(MPa) 17.7 14.9 RR Property² Rebound at 23° C. (%) 23.6 25.8 ¹Dataaccording to Rubber Process Analyzer as RPA 2000 instrument by AlphaTechnologies, formerly the Flexsys Company and formerly the MonsantoCompany. References to an RPA-2000 instrument may be found in thefollowing publications: H. A. Palowski, et al, Rubber World, June 1992and January 1997, as well as Rubber & Plastics News, April 26 and May10, 1993. ²Rebound is a measure of hysteresis of the compound whensubject to loading, as measured by ASTM D1054. Generally, the lower themeasured rebound at 0° C., the better the wet grip property. Generally,the higher the measured rebound at 23° C., the lower the rollingresistance. ³The G′ modulus at low temperatures can be readily bedetermined by a Metravib TM instrument at 1.5 percent strain and 7.8Hertz. The test method is understood to be similar to ISO 4664 and DIN53513.

TABLE 3 Composition E2 E3 E4 C2 C3 C4 Styrene-butadiene ¹ 30 30 30 30 3030 Polybutadiene, low cis ² 70 70 70 70 70 70 Softener ³ 30 15 30 15Antioxidant(s) 5 5 5 5 5 5 Stearic acid 5 5 5 5 5 5 Silane ⁴ 8.8 8.8 8.88.8 8.8 8.8 Silica ⁵ 140 140 140 140 140 140 Traction Resin C ⁶ 50 65 80Traction Resin A ⁷ 50 65 80 ZnO 2.5 2.5 2.5 2.5 2.5 2.5 Sulfur 1.2 1.21.2 1.2 1.2 1.2 Accelerator 6.0 6.0 6.0 6.0 6.0 6.0 ¹ Solutionpolymerized SBR with styrene content of 15% and 1,2-vinyl content of30%, Tg = −60° C. obtained from Trinseo as SLR3402. ² Solutionpolymerized low-cis PBD with 1,2-vinyl content of around 11%, Tg −90°C., and a Mooney viscosity of around 49 obtained from Trinseo as SEPB-5800. ³ Treated distillate aromatic extracts (TDAE) oil. ⁴ TESPD typesilane coupling agent. ⁵ Hi-Sil 315G-D precipitated silica from PPG witha CTAB surface area of 125 m²/g ⁶ Petroleum traction resin made of C5and C9 monomers, Tg = +38° C., with an aromatic hydrogen content ofaround 12 mole %, obtained as Oppera PR373 from ExxonMobil. ⁷ Copolymerof styrene and alpha-methylstyrene, Tg = +39° C., with an aromatichydrogen content of about 53 mole % obtained as Sylvatraxx4401 fromArizona Chemical.

TABLE 4 Composition E2 E3 E4 C2 C3 C4 Styrene-butadiene 30 30 30 30 3030 Polybutadiene 70 70 70 70 70 70 Softener 30 15 0 30 15 0 TractionResin (C) 50 65 80 0 0 0 Traction Resin (A) 0 0 0 50 65 80 Dynamicproperties¹ G′ at 1% strain (MPa) 1.8 1.5 1.7 2.3 2.3 2.5 Wet gripproperty² Rebound at 0° C. (%) 15.2 11.5 7.7 12.8 10.1 9.1 Lowtemperature property³ G′ at 1.5% strain, −20° C. 12.4 12.3 21.7 20.030.4 47.9 (MPa) RR Property² Rebound at 23° C. (%) 30.6 29.6 22.1 23.819.5 15.3

Example 2

In this example, a rubber composition featuring a blend of fullyfunctionalized low Tg polymers, high Tg plasticizers and high silicaloading is illustrated in inventive example E6 as shown in Tables 5 and6. Such composition is showing better rolling resistance performancereferring to rebound value at 23° C., better snow performances referringto storage modulus (G′) value at −30° C., better wet performancesreferring to rebound −10° C., maintained mileage referring to DinAbrasion data (relative volume loss) as compared to C5 and E5.

TABLE 5 Composition C5 E5 E6 Styrene-Butadiene, functionalized ¹ 40 4040 Polybutadiene, high cis ² 60 0 0 Polybutadiene, low cis ³ 0 60 0Polybutadiene, low cis, functionalized ⁴ 0 0 60 Silica 140 140 140Coupling agent 8.8 8.8 8.8 Oil 5 5 5 Resin ⁵ 62 62 62 ¹ Solutionpolymerized SBR with styrene content of 15% and 1,2-vinyl content of30%, Tg = −60° C. obtained from Trinseo as SLR3402. ² High cispolybutadiene, obtained as Budene 1223 from The Goodyear Tire & RubberCompany. ³ Low vinyl (11% vinyl), low cis polybutadiene, Tg about −90°C., and a Mooney viscosity of around 49 obtained from Trinseo as SEPB-5800. ⁴ Functionalized low vinyl (12% vinyl) low cis polybutadiene,Tg about −92 C. and functional groups reactive with hydroxyl groups onprecipitated silica, as BR1261 from Zeon. ⁵ Petroleum traction resinmade of C5 and C9 monomers, Tg = +38° C., with an aromatic hydrogencontent of around 12 mole %, obtained as Oppera PR373 from ExxonMobil.

TABLE 6 RR Property Rebound 23° C. (higher is better) 27.0 26.8 32.2 Lowtemperature Property G′ −30° C. (lower is better) MPa 33.9 29.3 23.1 WetGrip Property Rebound −10° C. (lower is better) 9.8 8.4 7.3 TreadwearProperty Din Abrasion (Relative volume loss, mm3) 92 148 102 (lower isbetter)

TABLE 7 Composition Cx Ex Styrene-Butadiene, functionalized ¹ 40 0Polybutadiene, high cis ² 60 0 Polybutadiene, low cis, functionalized ³0 100 Silica 140 150 Coupling agent 8.8 9.4 Oil 5 4 Traction Resin (C) ⁴62 0 Traction Resin (B) ⁵ 0 66 ¹ Solution polymerized SBR with styrenecontent of 15% and 1,2-vinyl content of 30%, Tg = −60° C. obtained fromTrinseo as SLR3402. ² High cis polybutadiene, obtained as Budene 1223from The Goodyear Tire & Rubber Company. ³ Functionalized low vinyl (12%vinyl) low cis polybutadiene, Tg about −92 C. and functional groupsreactive with hydroxyl groups on precipitated silica, obtained fromKumho Petrochemical as KBR820. ⁴ Petroleum traction resin made of C5 andC9 monomers, Tg = +41° C., with an aromatic hydrogen content of around12 mole %, obtained as Oppera PR373 from ExxonMobil. ⁵ Petroleumtraction resin made of DCPD/C9, Tg = +56° C., with an aromatic hydrogencontent of about 10 mole %, obtained as Oppera PR383 from ExxonMobil.

TABLE 8 RR Property Rebound 23° C. (higher is better) 27 35 Lowtemperature Property G′ −20° C. (lower is better) MPa 19 12 Wet GripProperty Rebound −10° C. (lower is better) 10 10 Treadwear Property DinAbrasion (Relative volume loss, mm3) 107 91 (lower is better)

TABLE 9 Composition Cx Ex Ex Styrene-Butadiene, functionalized ¹ 40 0 15Polybutadiene, high cis ² 60 0 0 Polybutadiene, low cis, functionalized³ 0 100 70 Natural rubber ⁴ 0 0 15 Silica 140 140 140 Coupling agent 8.88.8 8.8 Oil 5 5 5 Traction Resin (C) ⁵ 62 62 62 ¹ Solution polymerizedSBR with styrene content of 15% and 1,2-vinyl content of 30%, Tg = −60°C. obtained from Trinseo as SLR3402. ² High cis polybutadiene, obtainedas Budene 1223 from The Goodyear Tire & Rubber Company. ³ Functionalizedlow vinyl (12% vinyl) low cis polybutadiene, Tg about −92 C. andfunctional groups reactive with hydroxyl groups on precipitated silica,obtained from Kumho Petrochemical as KBR820. ⁴ Natural rubber, Tg about−60° C. ⁵ Petroleum traction resin made of C5 and C9 monomers, Tg = +41°C., with an aromatic hydrogen content of around 12 mole %, obtained asOppera PR373 from ExxonMobil.

TABLE 10 RR Property Rebound 23° C. (higher is better) 28 38 34 Lowtemperature Property G′ −20° C. (lower is better) MPa 17 8 11 Wet GripProperty Rebound −10° C. (lower is better) 10 12 9 Treadwear PropertyDin Abrasion (Relative volume loss, mm3) 109 107 121 (lower is better)

While certain representative embodiments and details have been shown forthe purpose of illustrating the subject invention, it will be apparentto those skilled in this art that various changes and modifications canbe made therein without departing from the scope of the subjectinvention.

1. A pneumatic tire having a tread comprising a vulcanizable rubbercomposition comprising, based on 100 parts by weight of elastomer (phr),(A) from about 45 to about 100 phr of a low-cis polybutadiene having avinyl-1,2 content ranging from 5 to 30 percent and a Tg ranging from−95° C. to −70° C.; (B) from about 0 to about 40 phr of a solutionpolymerized styrene-butadiene rubber having a glass transitiontemperature (Tg) ranging from −85° C. to −50° C.; (C) from 0 to 30 phrof natural rubber or synthetic polyisoprene; (D) from 0 to 20 phr of aprocess oil; (E) from 55 to 80 phr of a resin having an aromatichydrogen content ranging from 3 to 30 mole percent, the resin having aTg greater than 30° C.; and (F) from 110 to 160 phr of silica.
 2. Thepneumatic tire of claim 1, wherein the low-cis polybutadiene comprisesfrom 10 to 30 percent vinyl-1,2 content and from 15 to 45 percentcis-1,4 content.
 3. The pneumatic tire of claim 1, wherein the low-cispolybutadiene is a functionalized low-cis polybutadiene.
 4. Thepneumatic tire of claim 1, wherein the low-cis polybutadiene is afunctionalized low-cis polybutadiene functionalized with a least onemember of the group consisting of hydroxyl, amino, alkoxy, alkoxyamine,thiol, silane, alkoxysilane, and alkoxyaminosilane.
 5. The pneumatictire of claim 1, wherein the resin is a C5/C9 resin comprising 50-90%(by weight) piperylenes, 0-5% isoprene, 10-30% amylenes, 0-5% cyclics,0-10% styrenics, and 0-10% indenics.
 6. The pneumatic tire of claim 1,wherein the resin is a C5/C9 resin comprising 50-90% (by weight)piperylenes, 0-5% isoprene, 10-30% amylenes, 2-5% cyclics, 4-10%styrenics, and 4-10% indenics.
 7. The pneumatic tire of claim 1, whereinthe resin has an aromatic hydrogen content less than 25 mole percent. 8.The pneumatic tire of claim 1, wherein the resin has an aromatichydrogen content between 3 and 15 mole percent.
 9. The pneumatic tire ofclaim 1, wherein the solution polymerized styrene-butadiene rubber isfunctionalized with an alkoxysilane group and at least one functionalgroup selected from the group consisting of primary amines and thiols.10. The pneumatic tire of claim 1, wherein the oil is selected from thegroup consisting of aromatic, paraffinic, naphthenic, MES, TDAE, heavynaphthenic oils, and vegetable oils.
 11. The pneumatic tire of claim 1,wherein the solution polymerized styrene-butadiene rubber functionalizedwith an alkoxysilane group and a primary amine group, and is representedby the formula (1) or (2)

wherein P is a (co)polymer chain of a conjugated diolefin or aconjugated diolefin and an aromatic vinyl compound, R¹ is an alkylenegroup having 1 to 12 carbon atoms, R² and R³ are each independently analkyl group having 1 to 20 carbon atoms, an allyl group or an arylgroup, n is an integer of 1 or 2, m is an integer of 1 or 2, and k is aninteger of 1 or 2, with the proviso that n+m+k is an integer of 3 or 4,

wherein P, R¹, R² and R³ have the same definitions as give for theabove-mentioned formula (1), j is an integer of 1 to 3, and h is aninteger of 1 to 3, with the provision that j+h is an integer of 2 to 4.12. The pneumatic tire of claim 1, wherein the solution polymerizedstyrene-butadiene rubber is functionalized with an alkoxysilane groupand a primary amine group comprises the reaction product of a livingpolymer chain and a terminating agent of the formulaRN—(CH₂)_(x)—Si—(OR′)₃,  I wherein R in combination with the nitrogen(N) atom is a protected amine group which upon appropriatepost-treatment yields a primary amine, R′ represents a group having 1 to18 carbon atoms selected from an alkyl, a cycloalkyl, an allyl, or anaryl; and X is an integer from 1 to
 20. 13. The pneumatic tire of claim1 wherein the solution polymerized styrene-butadiene rubber isfunctionalized with an alkoxysilane group and a thiol, and comprises thereaction product of a living anionic polymer and a silane-sulfidemodifier represented by the formula(R⁴O)_(x)R⁴ _(y)Si—R⁵—S—SiR⁴ ₃ wherein Si is silicon; S is sulfur; O isoxygen; x is an integer selected from 1, 2 and 3;y is an integerselected from 0, 1, and 2; x+y=3;R⁴ is the same or different and is(C₁-C₁₆) alkyl; and R⁵ is aryl, and alkyl aryl, or (C₁-C₁₆) alkyl. 14.The pneumatic tire of claim 1, wherein the amount of thestyrene-butadiene rubber ranges from 20 to 40 phr.
 15. The pneumatictire of claim 1, wherein the amount of the low cis polybutadiene rangesfrom 55 to 80 phr.
 16. The pneumatic tire of claim 1, wherein the amountof the oil ranges from 1 to 20 phr.
 17. The pneumatic tire of claim 1,wherein the amount of the resin ranges from 55 to 80 phr.